[MARMAM] New paper: Preferred, small‑scale foraging areas of two Southern Ocean fur seal species are not determined by habitat characteristics

Mia Wege mia.wege at gmail.com
Wed Sep 18 17:01:51 PDT 2019


On behalf of all co-authors, I am pleased to announce the publication of
our article about habitat use by three closely situated fur seal colonies
at sub-Antarctic Marion Island and how environmental drivers that are known
to commonly influence fur seal foraging behaiviour, does not explain their
small-scale spatial segregation.

*Citation: *
Wege, M., de Bruyn, P.J.N., Hindell, M.A., Lea, M.A. & Bester, M.N. (2019).
Preferred, small-scale foraging areas of two Southern Ocean fur seal
species are not determined by habitat characteristics. *BMC Ecol.* *19*,
Article number: 36

This article, published in BMC Ecology is freely available at:


To understand and predict the distribution of foragers, it is crucial to
identify the factors that affect individual movement decisions at different
scales. Individuals are expected to adjust their foraging movements to the
hierarchical spatial distribution of resources. At a small local scale,
spatial segregation in foraging habitat happens among individuals of
closely situated colonies. If foraging segregation is due to differences in
distribution of resources, we would expect segregated foraging areas to
have divergent habitat characteristics.

We investigated how environmental characteristics of preferred foraging
areas differ between two closely situated Subantarctic fur seal (*Arctocephalus
tropicalis*) colonies and a single Antarctic fur seal (*A. gazella*) colony
that forage in different pelagic areas even though they are located well
within each other’s foraging range. We further investigated the influence
of the seasonal cycle on those environmental factors. This study used
tracking data from 121 adult female Subantarctic and Antarctic fur seals,
collected during summer and winter (2009–2015), from three different
colonies. Boosted Regression Tree species distribution models were used to
determine key environmental variables associated with areas of fur seal
restricted search behaviour. There were no differences in the relative
influence of key environmental variables between colonies and seasons. The
variables with the most influence for each colony and season were latitude,
longitude and magnitude of sea-currents. The influence of latitude and
longitude is a by-product of the species’ distinct foraging areas, despite
the close proximity (< 25 km) of the colonies. The predicted potential
foraging areas for each colony changed from summer to winter, reflecting
the seasonal cycle of the Southern Ocean. The model predicted that the
potential foraging areas of females from the three colonies should overlap,
and the fact they do not in reality indicates that factors other than
environmental are influencing the location of each colony’s foraging area.

The results indicated that small scale spatial segregation of foraging
habitats is not driven by bottom-up processes. It is therefore important to
also consider other potential drivers, e.g. competition, information
transfer, and memory, to understand animal foraging decisions and movements.

Thank you,
Mia Wege, PhD

Postdoctoral Fellow
Gateway Antarctica
School of Earth and Environment
College of Science
University of Canterbury

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